JBL 308P MKII Studio Monitor Review

[Maiky76]

Hi,

Before talking about EQ, here is a point I tried to make in the Adam T7V thread:
Adam T7V, EQ spinorama.

I just started to add the sub score as I have been asked several times was it was after EQing.
I don't really see the point of it or least the way I interpret it seems different.

Here is the calculation I perform, which seems to match what others are doing:
PPR_LF = 12.69 - 2.49*NBD_ON - 2.99*NBD_PIR - 4.31*log10(14.5) + 2.32*SM_PIR
see there for some details:
https://www.audiosciencereview.com/...urements-community-project.14929/#post-467858

This assumes:
- Frequency response 14.5Hz @-6dB. 14.5Hz is chosen so the theoretical max score is 10 although nothing prevent a system from achieving better performances and therefore the score could exceed 10; this is the first issue.
- Perfect integration whatever that might mean, which is the second issue and where I don't quite adhere to the concept.

The idea, I guess, is to compare speakers if the LF extension is literally taken out of the equation, akin the pound-for-pound rating.
To me it would make more sense to use it this way rather than thinking "if I buy a sub then I'll get the astonishing system predicted by the sub score". That is just not going to happen: sub or not the room will still determine the system LF response.

This being out of the way, here is my take on the EQ.
Score: 5.58, with sub: 7.31
Spinorama no EQ:

Directivity, wide horizontal coverage up to +/-20deg but better stay at tweeter height.

Contour plot:

EQ design:
I have generated two EQs. The APO config files are attached.

• The first one LW is targeted at making the LW flat.
• The second, Score, starts with the first one and adds the score as an optimization variable.
• The EQs are designed in the context of regular stereo use i.e. domestic environment, no warranty is provided for a near field use in a studio environment although the LW might be better suited for this purpose.
• The deviation from flat looks very small and might be related to production tolerance (example tweeter sensitivity is 1dB up) on this very unit rather than "designed-in" therefore the EQ here derived might not translate well on other units.

It seems like the EQs are acting more like tonal controls rather than trying to solve any significant issues.
ABX listening looks critical here.

Score EQ LW: 6.23 with sub: 7.93
Score EQ Score: 6.63 with sub: 8.23

JBL 308p mkII APO EQ LW 96000Hz
November092020-114203

Preamp: -1.3 dB

Filter 1: ON PK Fc 85.5 Hz Gain 1.27 dB Q 2.66
Filter 2: ON PK Fc 1013 Hz Gain -0.59 dB Q 3.79
Filter 3: ON PK Fc 1381 Hz Gain 1.9 dB Q 5.02
Filter 4: ON PK Fc 1599 Hz Gain -1.26 dB Q 8.42
Filter 5: ON PK Fc 2362 Hz Gain 1.21 dB Q 9.67
Filter 6: ON PK Fc 2871 Hz Gain -1.42 dB Q 0.43
Filter 7: ON PK Fc 3005 Hz Gain 0.98 dB Q 4.47
Filter 8: ON PK Fc 16165 Hz Gain -3.06 dB Q 6

JBL 308p mkII APO EQ Score 96000Hz
November092020-114055

Preamp: -1.2 dB

Filter 1: ON PK Fc 87 Hz Gain 1.23 dB Q 2.77
Filter 2: ON PK Fc 953 Hz Gain -0.89 dB Q 2.9
Filter 3: ON PK Fc 1384 Hz Gain 2.41 dB Q 5.79
Filter 4: ON PK Fc 1585 Hz Gain -1.13 dB Q 7.87
Filter 5: ON PK Fc 2395 Hz Gain 0.72 dB Q 6
Filter 6: ON PK Fc 2879 Hz Gain 1.72 dB Q 13.72
Filter 7: ON PK Fc 4189 Hz Gain -2.12 dB Q 0.29
Filter 8: ON PK Fc 16022 Hz Gain -4.23 dB Q 5.45

EQ design:

Zoom PIR-LW-ON

Regression - Tonal

EQ LW spinorama

EQ Score spinorama

Radar No EQ vs EQ score, appreciable improvements

Rest of the analysis is attached

Comparing with the other 8inch monitors
Kali LP8 vs Presonus Eris E8 XT, Spinorama and EQ design inside
Adam T8V
The 308p looks second to the LP8 with no EQ but the EQ versions would need careful listening for accurate evaluation.

 

[Robbo99999]

Two more notes on distortion:

1. This speaker absolutely, positively generates audible distortion at mid volumes and higher. Indeed anyone who says distortion is not audible, should experience it. It is very gradual and subtle at first and then gets to the point of being obnoxious. I do not hear such distortion in passive speakers driven by super powerful amplifiers. For near-field use though, you really have to listen loud to hear the distortions but it is definitely there and below the level of "going deaf."

2. This speaker has independent channels to woofer and tweeter. This means that harmonic distortion generated in bass does not travel to tweeter where it manifests itself as harshness. Standard passive speakers don't benefit this way so their bass distortion can result in different artifacts.

When you say "mid volumes" do you mean from position 5.5 on the volume dial on the back of the speaker if you drive it with 2V (or just under) on the input sensitivity switch on "consumer level" -10dBv setting? Or do you mean at mid dB levels, but from what kind of SPL onwards roughly would you say?

 

[JustIntonation]

I have the LP6 to still test.....

Looking forward to that one.
Suspect it will do better than the LSR305 and LSR308 overall.
I had the LSR305 mkII and LP6 side by side and it was clear as night and day that the LP6 was the better speaker. Also audibly lower distortion.

 

[amirm]

When you say "mid volumes" do you mean from position 5.5 on the volume dial on the back of the speaker if you drive it with 2V (or just under) on the input sensitivity switch on "consumer level" -10dBv setting? Or do you mean at mid dB levels, but from what kind of SPL onwards roughly would you say?

I don't know the SPLs. I am using my pre-amp volume control, not the setting in the back. The phrase was meant as what someone would say the loudness is, not a specific value.

 

[JohnBooty]

I have the 306P and during one spirited listening session they actually started to dance a bit. I put dumbbells on top to steady them. I can only imagine the 308P cry out for some more mass loading as well. However....

Is it entirely clear that the distortion comes from the loudspeaker-drivers ? I dont think so. I think its mostly depending on :

1. Lack of damping material inside the loudspeaker. The box is almost empty, making standing waves inside the loudspeaker to appear: - distortion. It should be about 3 or 4 times more of the damping material.
2. Lack of crossbracing inside the loudspeaker. The walls are vibrating like crazy: - distortion. Cured with a cross bracing L - to R wall.

All of these things are easily corrected by the owner, making this loudspeaker a ”kick-ass” loudspeaker, especially for the money.

I'd certainly think so as well. However, it may not be the case in reality. NoAudiophile had the same impulse, and modded the previous-generation version. He mass-loaded the baffle and damped the rear panel. His conclusion was that there was little to no measurable or audible improvement.

http://noaudiophile.com/JBL_LSR308/ (previously linked to in this discussion, but I'm not sure anybody mentioned his modification attempts)

However, he didn't attempt cross-bracing or damping of the side walls. And he measured frequency response only, not distortion. I would of course love to see somebody try cabinet modification experiments with the current-gen 308P.

 

[Dj7675]

Nice to see this speaker tested. I used 3 of these (one is the speaker Amir tested) in a home theater setup. I had sold off some DIY speakers and wanted something temporarily while I figured out what I wanted to do long term. A couple of observations:
1-Unpacking them, I was a bit shocked at how light they are for their size. Reminded me of an very inexpensive computer speaker.
2-They sounded very good. In particular dialogue was crystal clear. When measured in REW they measured very flat (no real downward tilt in my room), but didn’t sound bright to me.
3-Someone mentioned earlier, but is worth repeating... harmon nailed their objective with these if the goal was the best possible speaker at the lowest cost.
4-If used near a wall you get a crazy amount of bass that has to be dealt with. Otherwise the sound becomes very unbalanced. Also when running full range at loud levels, there was deep bass, but the bass sounded different to me (not sure how to describe it) than bass from a subwoofer. When crossed over at 80hz or so, it sounded more “right”’.

 

[Dj7675]

@RayDunzl any chance to do a distortion test of full range vs when crossed over @ 80hz? It would be interesting to see what affect crossing over at 80hz would have on distortion.

 

[RayDunzl]

@RayDunzl any chance to do a distortion test of full range vs when crossed over @ 80hz? It would be interesting to see what affect crossing over at 80hz would have on distortion.

Crossing out below 80Hz would be the same as starting the distortion sweep at 80Hz which would yield the same values for distortion for 80Hz and above.

 

[jcebedo11]

Hopefully the Mackie HR824 MK1 (discontinued) gets reviewed. It has a neutral frequency response, bass to 37hz, and it has decent internal bracing. Each speaker monitor weighs 32.6 pounds, which is a lot more and much more solid than the 308p.

 

[richard12511]

Looking forward to that one.
Suspect it will do better than the LSR305 and LSR308 overall.
I had the LSR305 mkII and LP6 side by side and it was clear as night and day that the LP6 was the better speaker. Also audibly lower distortion.

It's also cheaper than the 308(at least at non sale price). Would be impressive if it also outperformed.

 

[Chromatischism]

According to the AH review, the measurements are superb, but there's quite a hiss.

 

[andreasmaaan]

Two more notes on distortion:

1. This speaker absolutely, positively generates audible distortion at mid volumes and higher. Indeed anyone who says distortion is not audible, should experience it. It is very gradual and subtle at first and then gets to the point of being obnoxious. I do not hear such distortion in passive speakers driven by super powerful amplifiers. For near-field use though, you really have to listen loud to hear the distortions but it is definitely there and below the level of "going deaf."

2. This speaker has independent channels to woofer and tweeter. This means that harmonic distortion generated in bass does not travel to tweeter where it manifests itself as harshness. Standard passive speakers don't benefit this way so their bass distortion can result in different artifacts.

In which band(s) of the frequency spectrum did the distortion seem to be most audible?

 

[hestejoe]

I have the LP6 to still test.....

Is it plausible that we will have measures of it before this year's black friday?

 

[The Jniac]

If they had been able to keep the distortion down at 86dB, this thing could have been a top-shelf contender amongst everything tested here thus far.

 

[JustIntonation]

According to the AH review, the measurements are superb, but there's quite a hiss.

I guess you mean the Audioholics review of the Kali LP8?
I heard only the LP6 and assume it has the same level of hiss. The hiss of the Kali LP6 is about the same as the hiss of the JBL LSR305 mkII.
I assume the hiss is from the very cheap class D amp. Not a very good thing of course but when used farther away than nearfield it'll be almost gone.

 

[amirm]

In which band(s) of the frequency spectrum did the distortion seem to be most audible?

Bass to mid-range.

 

[turbotuff]

Hopefully the Mackie HR824 MK1 (discontinued) gets reviewed. It has a neutral frequency response, bass to 37hz, and it has decent internal bracing. Each speaker monitor weighs 32.6 pounds, which is a lot more and much more solid than the 308p.

Been begging a for this review for awhile!!

 

[Chromatischism]

If it's discontinued, wouldn't currently available models better warrant Amir's time?

 

[turbotuff]

If it's discontinued, wouldn't currently available models better warrant Amir's time?

They are still readily available in the used market and were an industry standard for years. Also anyone who knows Ethan Winer is familiar with his love affair for them.

 

[Xyrium]

Been begging a for this review for awhile!!

You could always send a pair in!

Just busting your chops. I'd love to see that old venerable design measured as well! I wonder if they've moved to Class D as many others have.

Edit: It appears that the new version is the XR line, using Class D amps, same driver complement though, it appears.